This invention relates to a method of implanting an intraocular lens in a human eye.
The natural eye in humans contains a lens which focuses images on the retina. Due to disease, naturally occurring processes or mutation, the lens may fail to function properly. For example, the lens, by mutation, may have been eliminated from the eye during its formation. Alternatively, the lens may be clouded at birth or become clouded over time. Clouding of a lens is known as a "cataract" which inhibits the transmission of visual information through the lens to the retina.
In the recent past, the removal of an impaired natural lens required a large incision into the eye at the juncture of the cornea and the sclera. As a result, healing time was substantial. Since the natural lens was removed, eyeglasses or external contact lenses were employed to help restore vision.
With the advent of intraocular lenses, incisions were still relatively large and healing time remained substantial. The length of the incision required for cataract removal initially remained substantially larger than that required for intraocular lens implantation.
Experience has shown that the longer the incision, the longer it takes to heal, the greater the danger of rupture of the incision post-operatively, and the greater the danger that poor healing will interfere with vision. Accordingly, efforts have continually been made to reduce the size of the incision. Such efforts have been successful in substantially reducing the size of the incision for cataract removal to the order of less than 8 mm, and even as small as 1.2 mm.
One proposal for reducing the length of the incision, which is the subject of U.S. Pat. No. 4,693,716 to the same inventor herein involves making the intraocular lens in multiple parts. Each part in inserted through the reduced incision and then the individual parts are assembled together in the eye. However, this technique, while permitting the use of a relatively small incision, requires special dexterity and handling by the surgeon of the multiple parts of the lens.
Another proposal for reducing the length of the incision requires the use of a very soft material for the lens, soft enough to permit the lens to be folded, inserted through the incision, and released. See, for example, U.S. Pat. No. 4,578,998. Such a lens is made in one embodiment from silicone and is extremely soft.
It is important, due to the delicate nature of certain eye structures, such as the cornea, that any intraocular lens be introduced into the eye in such a manner that it does not contact the cornea during its insertion and subsequent positioning. To accomplish this, instruments have been developed which grasp or otherwise enfold the foldable implant and accompany it through the surgical incision and into the eye, or through which the implant is injected, thus aiding in its insertion. All of these instruments, however, have the inherent disadvantage of increasing the size of the incision required for the insertion of the lens implant, since the incision must be large enough to accommodate both the implant and the instrument which grasps or enfolds the implant.
Current foldable lens implant methods require either a Bartell lens injector, or large forceps blades which fold the lens in half. These bulky, space occupying instruments increase the size of the incision required for lens insertion and may damage delicate ocular structures during and after their insertion into the eye.
Many prior art patents are devoted to techniques for improving the insertion of intraocular lenses. As an example, U.S. Pat. No. 4,439,878 discloses an intraocular lens structure for implantation in place of a cataractous natural lens. The construction features a lens element of the required prescription power and a multiple-sheet fenestrated haptic structure.
U.S. Pat. No. 4,484,515 discloses a haptic construction for an intraocular lens implant.
U.S. Pat. No. 4,249,272 discloses an intraocular lens structure. The lens features an adaptor structure assembled to an optically finished lens element having a plurality of angularly spaced stabilizing feet.
U.S. Pat. No. 4,849,271 discloses an intraocular lens structure having an adaptor structure assembled to an optically finished lens element.
U.S. Pat. No. 4,450,593 has an integral lens and haptic structure using composite laminated sheet material.
U.S. Pat. No. RE 31,968 discloses an intraocular lens having a light-focusing lens body and two position fixation means therefor.
U.S. Pat. No. 4,092,748 discloses an intraocular lens construction having a medial light-focusing lens body and two lateral position fixation elements therefor.
U.S. Pat. No. 4,174,543 discloses an intraocular lens with four-point fixation in the eyeball.
U.S. Pat. No. 4,253,200 discloses an intraocular lens with a medial light-focusing lens that includes oppositely disposed fixation means.
U.S. Pat. No. 4,840,979 discloses an intraocular lens structure which includes a first position fixation element connected to the lens which extends away from the same to the periphery of the iris for engagement in the posterior chamber.
U.S Pat. No. 4,870,760 discloses an intraocular lens which has at least a pair of position fixation elements providing multi-point support for the lens.
U.S. Pat. No. 4,268,921 discloses a multi-piece intraocular lens which includes a medial light-focusing lens body and a plurality of position fixation members for holding the lens body in proper position in the eye.
U.S. Pat. No. 4,296,501 discloses an intraocular lens which has a pair of position fixation elements providing a three-point support for the lens.
U.S. Pat. No. 4,408,454 discloses an intraocular lens having a fixation mechanism which includes a lens or optical portion having a resilient appendage attached to one end of the optical portion.
U.S. Pat. No. 4,838,687 discloses an intraocular lens having an appendage coupled to the lens portion which extends away from the lens portion to the periphery of the eye with there being a biasing means permitting movement of the appendage in relation to the lens portion.
U.S. Pat. No. 4,134,160 discloses an intraocular lens having an optical lens portion with there being an adjustable part which permits wedging of the intraocular lens beneath the optical portion of the cornea.
U.S. Pat. No. 4,159,546 discloses an intraocular lens having a plastic lens body and a plurality of flexible, memory-retaining and nonbiodegradable strands.
U.S. Pat. No. 3,991,426 discloses a posterior chamber artificial intraocular lens with a retaining means and instruments for use therewith, as does U.S. Pat. No. 4,053,953.
U.S. Pat. No. 4,056,855, U.S Pat. No. 3,711,870, U.S. Pat. No. 4,451,938, U.S. Pat. No. 4,477,931, U.S. Pat. No. 4,495,665, U.S. Pat. No. 4,585,457 and U.S. Pat. No. 4,578,998 all disclose other types of intraocular lens arrangements.